The changes are addition of a text entry field and the reorganisation of logic handling the Kross::Action. Note also that there is no code in mainwindow.cpp to set the label, as there was in the previous tutorial. Instead, Objects are simply made available to the scripting interface through the <tt>action->addObject</tt> calls, without any knowledge of what the script will use them for. This removes the need to know at the time of writing the application what function the scripts will perform, and is therefore suited to a plugin interface.

The changes are addition of a text entry field and the reorganisation of logic handling the Kross::Action. Note also that there is no code in mainwindow.cpp to set the label, as there was in the previous tutorial. Instead, Objects are simply made available to the scripting interface through the <tt>action->addObject</tt> calls, without any knowledge of what the script will use them for. This removes the need to know at the time of writing the application what function the scripts will perform, and is therefore suited to a plugin interface.

Line 107:

Line 119:

This script catches the textChanged SIGNAL of the QLineEdit, and connects it to a simple python function to reverse the string in the QLineEdit and display it in the QLabel.

This script catches the textChanged SIGNAL of the QLineEdit, and connects it to a simple python function to reverse the string in the QLineEdit and display it in the QLabel.

−

<code python>

+

<syntaxhighlight lang="python">

#!/usr/bin/env kross

#!/usr/bin/env kross

import MyLabel

import MyLabel

+

import MyInterpreter

import MyInputString

import MyInputString

Line 118:

Line 131:

MyInputString.connect("textChanged(const QString &)", reverseString)

MyInputString.connect("textChanged(const QString &)", reverseString)

−

</code>

+

</syntaxhighlight>

=== krossSigsSlots.js ===

=== krossSigsSlots.js ===

−

This script does the same like the script above but using the JavaScript scripting language.

+

This script does the same as the script above but using the JavaScript scripting language.

It is possible to connect signals from your Object to slots in your script file automatically. Edit the mainwindow.cpp file to add another argument to the addObject function:

It is possible to connect signals from your Object to slots in your script file automatically. Edit the mainwindow.cpp file to add another argument to the addObject function:

−

<code cpp>

+

<syntaxhighlight lang="cpp">

−

action->addObject(txtInputString, "MyInputString",

+

action->addObject(txtInputString, "MyInputString",

−

Kross::ChildrenInterface::AutoConnectSignals);

+

Kross::ChildrenInterface::AutoConnectSignals);

−

action->addObject(cmbInterpreter, "MyInterpreter");

+

−

action->addObject(lblMessage, "MyLabel");

+

action->addObject(cmbInterpreters, "MyInterpreter");

−

</code>

+

action->addObject(lblMessage, "MyLabel");

+

</syntaxhighlight>

The <tt>Kross::ChildrenInterface::AutoConnectSignals</tt> argument causes signals of the object to be automatically connected with scripting functions of the same name. Therefore, the scripts can again be simplified:

The <tt>Kross::ChildrenInterface::AutoConnectSignals</tt> argument causes signals of the object to be automatically connected with scripting functions of the same name. Therefore, the scripts can again be simplified:

=== Simplified scripts ===

=== Simplified scripts ===

−

The python function reverses the string:

+

The following python code provides a function that reverses the string:

−

<code python>

+

<syntaxhighlight lang="python">

−

#!/usr/bin/env kross

+

−

+

import MyLabel

import MyLabel

Line 155:

Line 168:

s = s[::-1]

s = s[::-1]

MyLabel.text = s

MyLabel.text = s

+

</syntaxhighlight>

−

</code>

+

Now follows a javascript function that converts the string to [http://en.wikipedia.org/wiki/Pig_Latin pig latin]:

So far this tutorial has described connecting signals in c++ objects with slots in scripts. The objects published to kross scripts also make their signals available to the scripts. The signals can then be emitted by calling them. This is equivalent to calling:

+

+

<syntaxhighlight lang="cpp">

+

emit signalName();

+

</syntaxhighlight>

+

in c++ code. To illustrate this, change the python script to emit the setEnabled(bool) signal of the QCombobox:

+

+

<syntaxhighlight lang="python">

+

#!/usr/bin/env kross

+

+

import MyLabel

+

import MyInterpreter

+

+

def textChanged(s):

+

if s == "off":

+

MyInterpreter.setEnabled(False)

+

elif s == "on":

+

MyInterpreter.setEnabled(True)

+

s = MyInputString.text[::-1]

+

MyLabel.text = s

+

</syntaxhighlight>

+

+

If 'off' is written in the text field, the setEnabled signal is emitted and the combobox is greyed out. It is not re-enabled again until 'on' is written in the text field.

−

{{TODO|Stop this crashing when the user makes a second selection from the combo box.}}

+

This is a simple demonstration of signal-slot relationships using kross. More complex interfaces may be written to complete a plugin architecture.

Latest revision as of 19:47, 29 June 2011

This page is under construction. This page is actively being developed and updated with new information, and may be incomplete. You can help by editing this page

This tutorial shows how to use a system of signals and slots to provide a scripting interface for a KDE application. It builds upon the Kross Hello World tutorial and again follows a 'Hello World' type format.

Update source files

This tutorial is based on the Hello World tutorial and extends the codebase we wrote there with new functionality.

mainwindow.h

First edit the mainwindow.h to handle the changes to mainwindow.cpp. Note that the change is the addition of a private Kross::Action .

#ifndef MAINWINDOW_H#define MAINWINDOW_H#include <QComboBox>#include <QLabel>#include <QLineEdit>#include <kross/core/action.h>// The main window to display our combobox and the label.classMainWindow:publicQWidget{Q_OBJECTpublic:// The constructor.MainWindow(QWidget*parent=0);privateQ_SLOTS:// This slot is called when the item in the combobox is changed.voidinterpreterActivated(constQString&);private:QLineEdit*txtInputString;QLabel*lblMessage;QComboBox*cmbInterpreters;// We now have the action as class-member.Kross::Action*action;};#endif

mainwindow.cpp

Using the same CmakeLists.txt and main.cpp from the previous Hello World tutorial, edit the mainwindow.cpp as follows:

#include "mainwindow.h"#include <QVBoxLayout>#include <QDebug>#include <kross/core/manager.h>#include <kross/core/action.h>// the constructor.MainWindow::MainWindow(QWidget*parent):QWidget(parent){txtInputString=newQLineEdit();lblMessage=newQLabel("Hello");cmbInterpreters=newQComboBox();cmbInterpreters->addItem("Choose Interpreter","");foreach(QStrings,Kross::Manager::self().interpreters())cmbInterpreters->addItem(s);connect(cmbInterpreters,SIGNAL(activated(constQString&)),SLOT(interpreterActivated(constQString&)));QVBoxLayout*vLayout=newQVBoxLayout;vLayout->addWidget(cmbInterpreters);vLayout->addWidget(txtInputString);vLayout->addWidget(lblMessage);setLayout(vLayout);// This time we create the Kross::Action already within the// constructor and add the objects that should be accessible// from within scripting code.action=newKross::Action(this,"MyScript");action->addObject(txtInputString,"MyInputString");action->addObject(cmbInterpreters,"MyInterpreter");action->addObject(lblMessage,"MyLabel");}// this slot is called when the active item of the combobox changes.voidMainWindow::interpreterActivated(constQString&strSelectedInterpreter){if(strSelectedInterpreter.isEmpty()){lblMessage->setText("-");return;}// this time we are using external script files.QStringfilename;if(strSelectedInterpreter=="python")filename="krossSigsSlots.py";elseif(strSelectedInterpreter=="javascript")filename="krossSigsSlots.js";elsereturn;// set the script file that should be executed.action->setFile(filename);// finally execute the scripting code.action->trigger();}

The changes are addition of a text entry field and the reorganisation of logic handling the Kross::Action. Note also that there is no code in mainwindow.cpp to set the label, as there was in the previous tutorial. Instead, Objects are simply made available to the scripting interface through the action->addObject calls, without any knowledge of what the script will use them for. This removes the need to know at the time of writing the application what function the scripts will perform, and is therefore suited to a plugin interface.

krossSigsSlots.py

This script catches the textChanged SIGNAL of the QLineEdit, and connects it to a simple python function to reverse the string in the QLineEdit and display it in the QLabel.

The Kross::ChildrenInterface::AutoConnectSignals argument causes signals of the object to be automatically connected with scripting functions of the same name. Therefore, the scripts can again be simplified:

Simplified scripts

The following python code provides a function that reverses the string:

importMyLabeldeftextChanged(s):s=s[::-1]MyLabel.text=s

Now follows a javascript function that converts the string to pig latin:

Emitting signals from within scripts

So far this tutorial has described connecting signals in c++ objects with slots in scripts. The objects published to kross scripts also make their signals available to the scripts. The signals can then be emitted by calling them. This is equivalent to calling:

emitsignalName();

in c++ code. To illustrate this, change the python script to emit the setEnabled(bool) signal of the QCombobox: